Retainer for coal cutter bits



P 27, 1966 R. F. PROX, JR

RETAINER FOR COAL CUTTER BITS Filed April 17, 1964 INVENTOR ROBERT F. PROX,JR.

g I a ATTORNEYS.

United States Patent 3,275,376 RETAINER FOR COAL CUTTER BITS Robert F. Prox, Jr., West Terre Haute, Ind., assiguor to Frank Prox Company, Inc Terre Haute, Ind., a corporation of Indiana Filed Apr. 17, 1964, Ser. No. 360,720 7 Claims. (Cl. 299-92) This invention relates to coal type mining machinery, more particularly to a resilient detent for the holding of mining cutter bits in a cutter chain or bar socket.

Mining operations, such as the undercutting of coal or potash are presently accomplished by utilizing large all assemblies in which the various chain links or bars are provided with sockets, and the cutter bits have shank elements for engagement and retention of the cutter bit shanks in the sockets.

The efficiency of such machines depends on the ease with which cutter bits may be replaced. Besides the problem of the bits dulling rather rapidly, vibration and shock breaks a large number of them. To replace bits, an entire machine must be shut down, the dulled or broken bits removed from their sockets where they are generally held by some form of retainer, and new bits inserted. Since in this type of machinery, the cutter bits are subjected to rapid wear and abrasion as well as vibration it is a problem to design a detent means for holding a cutter bit shank in a socket for resisting loosening, allowing quick replacement of the cutter bit, and still being easily replaceable itself.

A number of detent devices have been developed and are now in use in the industry. One conventional method for providing such a result is by attaching the cutter bit shanks within their sockets with set screws biased against the face of the shank or fitting into a hole therein. It has been found, however, that a set screw is slow to release, and with the ever present coal dust and rock chips found in a mine, the head and thread channels are soon filled. The operator must go through the time consuming step of cleaning oil the head of the screw before loosening it and then may find that it takes an inordinate force to turn the dirt clogged threads. In hurrying to replace hits, it has been found that it is not uncommon for the threaded apertures and respective set screws to become cross threaded and therefore no longer even able to hold the bits in the socket member or the excessive pressure needed to turn the dirt clogged threads may cause the operator to think that the connection is tight while in reality the shank of the cutter 'bit is not being gripped at all but is merely laying loosely in the socket. A set screw can also vibrate loose from the action of the machine and the bit pull out when lodged in an especially hard vein of coal. Since the socket members are an integral part of the mining machinery, the machinery must be completely halted to allow the damaged socket or a lost cutter bit to be These resilient retainers are usually in the form of plungers operating in bores perpendicular to the shank of a bit with the metallic head abutting a notch in the shank of a 'bit and allowing movement back along the axis of the bore when sufllcient pressure is applied as during the cutter bit insertion and removal. A most recent development in the field is that of a retainer operating in a bore traversing the socket member from side to side and having a section intersecting the cutter ibit socket passage. In this instance the metallic abutting means either has been a bar which extends across a notch in the cutter bit shank and is anchored by its ends in a elastomeric backing material, or is a finger based in the elastomer and extending into the intersection of the passages.

These resilient detent means, although a comparatively successful alternative, are still subject to extreme wear and lose their resiliency at which time they must be replaced. The elastomeric portion tends to deteriorate, becoming gummy or sticky and making removal difficult. Also to prevent the rotation of the detent element to a position in which the metallic portion is not facing the intersection, the retainer must be keyed in position. A simple expedient is a slot extending the length of the detent passage and an integral key, formed of the elastomer. However, an integral elastomeric key will not last the life of retainer due to the tearing action of the rotative forces and the efiects of deterioration on this thin section.

With the designs utilizing metallic bars or fingers, a tree portion of the metal abutting element extends into the cutter bit socket and the cutter bit shank notch or cavity, and continued shock on the unsupported free portion of the abutting element may cause untimely failures.

.The finger type of detent may even be torn loose from its anchorage in the elastomeric backing material and fall into the socket when the contained cutter bit is removed. Also, it takes considerable force to remove a bit from a socket, the loss of a cutter bit head preventing removal of the remainder of the bit without disassembly of the unit, since the finger interlocks with the notch in the shank, preventing the retainer from being removed instead. Furthermore, devices having a metal detent embedded Within the estomer are more costly than other competing resilient retainers.

One of the principal objects of this invention is the provision of a resilient detent means which does not suffer from the above defects.

Another object of the invention is the provision of a resilient detent means which does not depend for its action on a reciprocating plunger.

A further object of the invention is the provision of a detent means fabricated so as to be easily removed from the socket member regardless of the condition of the elastomeric backing material.

A still further object of the invention is the provision of a detent means in which the metallic abutting means is not subject to breakage as in prior art devices.

A further object of the invention is the provision of a detent means having a metallic abutting means which can not become displaced as long as the retainer is fixed within the socket.

A still further object of the invention is the provision of a detent means which may be removed from the socket without the prior removal of the held cutter bit.

Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view of a cutter bit secured in a socket member by the resilient detent of the present invention;

FIGURE 2 is a side elevational view, partially broken 22 of less than 180, and preferably about 90.

way slot 23 cut in the wall of the retainer passageway 22 and extends the length thereof.

r, O away, illustrating the method of inserting a cutter bit into the socket member;

FIG. 3 is a longitudinal view taken along the lines 3-3 1 of FIG. 1;

FIG. 4 is an exploded perspective view of the resilient detent of the invention illustrating the shapes of each of :14 of a socket member, generally designated 16,: and extends outwardly from the upper face 18 thereof. A resilient detent, generally designated 20, which releasably secures the cutter bit in the socket member 16, resides in a circular horizontal passageway 22 in the rectangular body portion 14 intersecting the rectangular vertical bit holding passageway 12 over an are a of the passageway A keyopposite the intersection with the cutter .bit holding passageway 12,?is parallel to the axis of the passageway 22' A pair of rectangular legs 24 extend vertically downward from the base of the socket member body portion 14 for connecting the socket member to the chain or bar of a coal cutting machine (not shown) in a manner well known in the art.

The cutter bit 10, as shown best in FIG. 5, has a head portion 26, with a cutting portion 32 formed on one upper edge, and a shank 28, with an integral rectangular flange 30 formed therebetween. The shank portion 28 of the cutter bit 10 is substantially rectangular in cross-section for mating with the passageway 12 of the socket member 16 while the lower face 34 of the flange forms a flat surface for abutting the upper surface 18 of the body portion 14 upon insertion of the cutter bit shank 28 into the bit holding passageway in the socket-member 16. The shank 28 has a pair of parallel planer side faces 36, a planer front face 38, and a rear face, generally designated 1 40. The rear face 40 has a contoured notch 42 formed transversely across the surface thereof to mate with the detent 20, the notch 42 consisting of a curved section 44 and an upper camming section 46. The upper camming section 46 extends downward and outward from the inner end of the curved section 44 to the plane of the rear face .npper camming section 46. The lower ends of the side faces 36 have converging lower sections 54 meeting approximately at the lower face 50 to form a wedge shaped profile. i i

The resilient retainer 20' consists of; a substantially cylindrical block 56 of an elastomeric material such as rubber, a metallic abutting element 58, and a metallic cover plate 60. The elastomeric block 56 has an integral: key flange 62 extending along a portion of one side thereofparallel to the axis of the cylinder 56. The cover. plate vconsisting of a spring steel sheet stamped to conform to, the surface of the cylinder including the key flange 62, is molded into the surface and contiguous therewith, to form a reinforced key. The angle B of the sector of the cylinder 56 covered by the plate 60 is less than 180.

Opposite the key 62, a planar bottomed section 64, not extending to either end, is removed from the cylinder 56 and the metallic abutting element 68, similarly shaped, Y is molded therein forming a contiguous surface of metal,

and elastomer. The angle 7 between the ends of the sectron 64 and the axis of the cylinder is preferably less than 180 but greater than the angle a which denotes the arc of the cylinder 56 extending into the intersection of the passageways 12, 22. A rectangular compression slot 66, may be formed on each side of the cylinder 56, parallel to the axis thereof, between each side of the cover plate 60 and the abutting element 58, without extending all the way to the ends of the cylinder 56,

Before a cutter bit is to be inserted into the socket member 16, the resilient retainer 20 is placed in the retainer passageway 22 with the. key 62,1 and its formed cover plate portion 60, fitting into the keyway 23 and a portion of the abuttingelement 58 lying within the intersection of the retainer passageway 22 with,the cutter bit socket passageway 12.

In operation, when a cutter bit 10 is to be inserted into the socket member 16 (solid lines FIG. 2) the lower camming section 48 drives the abutting element 58 out of the rectangular cutter bit passageway 12 by compressing 1 the cylindrical elastomer block 56. As the cutter bit 10 continues to descend, the abutting element 58 passes the apex 52 and moves into the notch 42 allowing the clastomer to expand and drive the element 58 back into, the intersection of the passageways 12, 22, against the upper camming section 46 of the shank 28 to urge the cutter bit 10 downward and to hold the bit 10 securely in place (in apex is passed, after which the ;re-expanding cylindrical block 56 drives against the lower camming section'148 urging the cutter bit 10 upward.- To reduce the pressure required to insert a cntterbit 10 into, the socket16,compressions slots 66, as shown may be cut into the sides of the block 56. If such slots 66' are used, they should not extend to the ends of the cylindrical block 56 so as to prevent the accumulation of dirt in the open spaces which would impair their functions.

The resilient detent 20 may be easily removed, even when the elastomer has partially decomposed, due to the design of the plate 60 which covers the key flange, 62 in the keyway 23. The cover plate 60 also shields nearly /3 of the surface area of the elastomeric cylinder 565 allowing only enough of the elastomer surface free to f contact, the walls of, the retainer passageway 22 as is needed to provide the necessary frictional engagement to prevent accident axial movement of the resilient retainer 20. The particular design of the resilient detent 20 permits the use of a short abutting element 58',{supported;

along its entire length by the elastomer backing to prevent the block 56 extends into the intersection of the passage ways 12, 122, the abutting element 58 can never fallinto the socket passageway 12 even if the. bond holding the element 58in the cut-out 64 in the blade 56 should fail.

55' Moreover the designof the abutting element 58 of the,

retainer 20, to extend completely across the intersection 28 ofthe cutter bit 10, permits the retainer. 20 to be driven out of the passageway 22 to release the cutter bit 10 if the head portion of the bit 10 has broken off so that the proper force can no longer be applied to the ,bit'10 to cam it up and out past a retainer 20 in place in passageway 22. I a V While'the forms oflappara'tus herein described constitute a preferred embodiment of the invention, it is to be.

understood that the invention is not limited to this precise is defined in the appended claims.

Iclaim: k 1., In combination; a socket member, first and second intersecting passageways each extending through said socket member, an interconnecting aperture formed by the intersecting of said passageways, acutter bit, said cutter bit having a head section and a shank section, said which 1 shank section being slidably fitted through said first passageway in the socket member; detent means; said detent means being fixed against rotation in said second passageway to releasably secure said cutter bit shank in said first passageway; said detent means comprising an elongated estomeric cylinder, 'a cut-out section midway along said cylinder, non-yielding abutting means, said abutting means being fixed in said cut-out so as to form a contiguous surface with the elastomeric cylinder, said abutting means being resiliently fixed adjacent the intersection of said first and second passageway-s when the detent means is fixed in the second passageway to releasably secure the cutter bit shank in the first passageway.

2. The combination of claim 1 in which rotation of said cylinder in said second passageway is prevented by means comprising a slot in the wall of said second passageway and extending the length thereof and an integral elongated flange on the cylinder, said flange adapted to fit into said slot when said abutting means lies in the intersecti-on of the first and second passageways.

3. The combination of claim 2 in which a non-yielding element extends over a portion of said cylinder including said flange, formed to the shape of said cylinder and flange said element being fixed to the surface of said cylinder.

4. The combination of claim 1 wherein the surface of said abutting means, which forms a contiguous surface with said elastorneric cylinder a greater surface area than that of the aperture formed by the intersection of the second passageway and the first passageway.

5. A resilient detent means consisting of; a elastomeric cylinder, an integral flange extending from the surface of said cylinder parallel to the axis thereof, a cutsout section midway along the length of the cylinder opposite said flange, a rigid abutment means, said abutment means being shaped identically to the cut-out in the cylinder, means fixing said abutment means in the cut-out in the cylinder so as to form a contiguous surface including the elastomeric material and the abutment means.

'6. The combination of claim 5 wherein there is a plate fixed to said cylinder extending over at least a portion of said integral flange, said plate being shaped to conform to the surface covered.

7. The combination of claim 6 wherein at least one extended compression slot is formed in the cylinder between a side of said abutment means and said shaped plate.

References Cited by the Examiner UNITED STATES PATENTS 2,279,960 3/1942 Terry 27919.5 2,852,874 9/1958 Grubb 37142 2,994,140 8/1961 Launder 37--'142 3,019,537 2/1962 Stephenson 8.3 X 3,088,721 5/1963 Krekeler 299-92 3,116,052 12/1963 Osgood 299-92 ERNEST PURSER, Primary Examiner, 

1. IN COMBINATION; A SOCKET MEMBER, FIRST AND SECOND INTERSECTING PASSAGEWAYS EACH EXTENDING THROUGH SAID SOCKET MEMBER, AN INTERCONNECTING APERTURE FORMED BY THE INTERSECTING OF SAID PASSAGEWAYS, A CUTTER BIT, SAID CUTTER BIT HAVING A HEAD SECTION AND A SHANK SECTION, SAID SHANK SECTION BEING SLIDABLY FITTED THROUGH SAID FIRST PASSAGEWAY IN THE SOCKET MEMBER; DETENT MEANS; SAID DETENT MEANS BEING FIXED AGAINST ROTATION IN SAID SECOND PASSAGEWAY TO RELEASABLY SECURE SAID CUTTER BIT SHANK IN SAID FIRST PASSAGEWAY; SAID DETENT MEANS COMPRISING AN ELONGATED ESTOMERIC CYLINDER, A CUT-OUT SECTION MIDWAY ALONG SAID CYLINDER, NON-YIELDING ABUTTING MEANS, SAID ABUTTING MEANS BEING FIXED IN SAID CUT-OUT SO AS TO FORM A CONTIGUOUS SURFACE WITH THE ELASTOMERIC CYLINDER, SAID ABUTTING MEANS
 5. A RESILIENT DETENT MEANS CONSISTING OF: A ELASTOMERIC CYLINDER, AN INTEGRAL FLANGE EXTENDING FROM THE SURFACE OF SAID CYLINDER PARALLEL TO THE AXIS THEREOF, A CUT-OUT SECTION MIDWAY, ALONG THE LENGTH OF THE CYLINDER OPPOSITE SAID FLANGE, A RIGID ABUTMENT MEANS, SAID ABUTMENT MEANS BEING SHAPED IDENTICALLY TO THE CUT-OUT IN THE CYLINDER, MEANS FIXING SAID ABUTMENT MEANS IN THE CUT-OUT IN THE CYLINDR AS TO FORM A CONTIGUOUS SURFACE INCLUDING THE ELASTOMERIC MATERIAL AND THE ABUTMENT MEANS. 